Year	gross (GPI)
1971	0.996500015258789
1972	0.998000025749207
1973	0.999610006809235
1974	1.00063002109528
1975	0.994490027427673
1976	0.991550028324127
1977	0.991559982299805
1978	0.990809977054596
1979	0.990209996700287
1980	0.989069998264313
1981	0.986869990825653
1982	0.987659990787506
1983	0.986029982566834
1984	0.984790027141571
1985	0.992529988288879
1986	0.994719982147217
1987	0.996630012989044
1988	0.999130010604858
1989	0.998960018157959
1990	0.997169971466064
1991	0.996020019054413
1992	0.99617999792099
1993	0.995559990406036
1994	0.996039986610413
1995	0.995660006999969
1996	0.998849987983704
1997	1.00308001041412
1998	1.00972998142242
1999	1.01723003387451
2000	1.02230000495911
2001	1.02444005012512
2002	1.02336001396179
2003	1.02265000343323
2004	1.02003002166748
2005	1.01584005355835
2006	1.01273000240326
2007	1.00897002220154
2008	1.00641000270844
2009	1.00232994556427
2010	0.998239994049072
2011	0.997259974479675
2012	0.99602997303009
2013	0.997080028057098
2014	0.997500002384186
2015	1.00029003620148
2016	0.999779999256134
2017	0.999899983406067
2018	0.998910009860992
2019	0.999210000038147
2020	0.998040020465851